The charging of a battery pack is limited by many factors among which temperature is a very important factor. In order to shorten the waiting time for discharging or charging a battery pack, a conventional battery pack charging device generally employs a fan to reduce temperature to thereby ensure that the battery pack in the charging device or a charging module is at an appropriate working temperature. Some battery packs with large power generate a lot of heat and need to use high power fans, thereby producing high noise. An appropriate temperature during the charging of the battery pack is capable of shortening the charging duration of the battery pack. Additionally, a typical high power fan for a charging device rotates at a constant rotational speed during the charging, and causes waste of electrical energy.